1. Field of the Invention
This invention relates to an elastic crawler for use in a crawler-type traveling apparatus adopted for traveling part of an agricultural machine such as a half-tractor or a combine, a construction machine such as a back-hoe, or an automobile, and is employed, for example, as a core-metalless elastic crawler (called also rubber crawler free of core metal) in which a core metal is not buried within a crawler main body of the crawler.
2. Description of the Related Art
A conventional crawler-type traveling apparatus adopted on a traveling part of agricultural or construction machine is structured, mainly, with an endless strip-formed crawler belt (covering belt) stretched over a driving wheel, an idler (follower wheel) and a plurality of rollers. By drivably rotating the driving wheel, the crawler belt is circulated along the circumferential direction, thereby enabling the machine to travel.
There exists, as the crawler belt, an elastic crawler having a crawler main body formed of a rubber-like elastic material into an endless belt and configured to convey drive power from the driving wheel through the driving projections provided in an inner surface of the crawler main body.
The elastic crawler has a core-metalless structure in which a core metal extending between the right and left ends of the crawler is not buried in the crawler main body.
Meanwhile, the crawler-type traveling apparatus adopting such a core-metalless elastic crawler employs outer-flanged type rollers rolling on right and left side regions in the inner surface of the crawler body. The crawler body is formed with right and left side regions having substantially uniform thickness (generally even thickness) entirely in the widthwise direction of the crawler.
As the size of the main body of the machine adopting the crawler-type traveling apparatus increases, the conventional elastic crawler also increases in its width in order to keep low ground contact pressure. This requires broadening the width of the roller, correspondingly. However, there is a limitation in broadening the width of the roller in view of increases in costs, weight, and so on.
In the case that the elastic crawler has such a broad width that its side regions largely extend out of the roller in the widthwise direction of the crawler, when the elastic crawler at the side region runs over a projection, a marginal stone or the like, as shown in FIG. 13, the crawler body 20 at its side region 20a is bent about a portion 23 of the crawler body 20 corresponding to the right and left ends of outer peripheral surface of the roller 21. As a result, the bent portion is stretched on a ground-contacting surface side (stress concentration takes place in that portion) and, hence, crack might occur if the bent portion is in contact with a sharp obstacle.
Further, increases in lug height tend to trigger further local elongations due to a twist (entanglement) of the lug. Besides, during running over, clamping or swivel at a construction site with riprap or sharp matters, the crawler possibly encounters stretch and cut damage.